Welp, the gig was last Friday. First one in a year and a half! We hit a lot of clams but most probably not audible out front, and were nonetheless well received - got the docile crowd moving a bit; some friends who had not seen us came along; they were a bit astonished that we were actually good. You know how it is, you go to a friend's show and try to think of something polite afterward ;-)
I did indeed use the house rig, but running the Genz-Benz as a preamp. A quick look behind the amp revealed 1) the cab only had 1/4" inputs and I had neglected to bring suitable cables, but 2) the SWR head had an effects return. I was sure the SWR would have plenty of power, and the GB power amp isn't a huge factor in what I like about its sound, so I happily plugged the effects send from the Genz-Benz into it, tweaked knobs, and was off and running. I'm glad I did - I could probably have got something usable out of the SWR preamp, but I'm not super familiar with them, and it has too many knobs to learn in a five-minute setup with no soundcheck
The house cab was disappointing though. I read the backline list from the club and stupidly assumed that "SWR 750 head with 410 cabinet" meant an SWR cabinet. I don't know what that cab was, but it was not an SWR, and was rather mushy sounding both out front and on stage. Oh well. I was able to work with it by dialing up the upper mids, but next time may go back to bringing my EA cabs. It's worth being happy with the cabs!
I ended up bringing the LPB-1 instead of the Greco T-bird because, after bringing both along to recent practices, I was reminded that the Greco, while having insane amounts of mids and therefore always very audible, is not particularly defined. The LPB-1 is tighter and sits in our band's twin-guitar sound better. It can be hard to get a good mix with three loud Gibsons on stage